The impact of agricultural activities on biodiversity of plants and animals has a long history, which began when humans first started the domestication process over 7000 years ago (Solbrig and Solbrig, 1994). By selecting a few seemingly more useful or edible species, these ancient agriculturists began the selection process which still continues today as farmers, researchers and companies look for more productive plants and animals. This process necessarily involves a reduction and simplification of the immense biological diversity of nature, at both the species and genetic level. However, since the first farmers selected their preferred plants and cultivated their land with the few simple tools and mostly organic inputs available at a local (small) scale, their activities were, in general, of low impact or at least of a limited geographical scale. There are still examples today of cultures that continue to practice this small-scale, limited impact agriculture (Denevan, 1995; Redford and Mansour, 1996).
The growth in population and the increasing urbanization led to the need to produce larger quantities of food being transported over longer distances. Larger areas of land were dedicated to agricultural activities, using animal traction, irrigation canals and other intensification techniques. The change in land use through clearing forested or grassland for cultivation, changes in agricultural practices such as crop rotation and mixes, grazing practices, residue management, irrigation and drainage all affect the soil environment and change the range of habitats and foods for soil organisms. Treatments applied to land such as liming, fertilisers, manure and other organic materials, tillage practices, the use of pesticides and so forth, all change the physical and chemical environment.
With the urbanization of the population, proportionally fewer number of people were involved in food production. This led to changes in agricultural practices such as the development of modernized agricultural techniques with the use the moldboard plow, motorized tractors, hybrid cultivars, inorganic fertilizers and pesticides. This created new pressures on the land, dramatically increasing the influence of agricultural practices on biodiversity.
Today, some 6 billion humans rely on biodiversity for its goods and services, the population having doubled since 1950. This may reach 9 billion by the year 2050. More significantly, the demands on natural resources are growing even faster, the global economy having quintupled in the last 50 years. As the amount of land available for agricultural use continues to decrease worldwide, the demands of human populations (especially urban) are simultaneously increasing, putting more pressure on the soil resource base and the environment (Lavelle, 2000; Young, 1998).